Astroviruses are known to infect a variety of avian and mammalian species and typically cause diarrhea. Clinical symptoms usually last 2-4 days and consist of watery diarrhea and, less commonly, vomiting, headache, fever, abdominal pains, and anorexia. They are thought to be host specific with little evidence for cross-species transmission. In humans, 8 serotypes of astroviruses have been described (Mendez, E., et al., Fields Virology. 5th ed., Knipe, D. M., Howley, P. M., editors, Lippincott Williams & Wilkins, Philadelphia, Pa. (2007) 981-1000. Recently, a novel astrovirus (Astrovirus MLB1) (Finkbeiner, S. R., et al., Virol J. (2008) 5:117; Finkbeiner, S. R., et al., PLoS Pathog (2008) 4:e1000011) and a novel picornavirus (Cosavirus E1) (Holtz, L. R., et al., Virol J. (2008) 5:159) were identified in diarrhea patients by the present inventors.
Human astroviruses have been associated with up to ˜10% of sporadic cases of viral diarrhea in children and with 0.5-15% of outbreaks. Significantly, in some reports the etiologies of 12-41% of the outbreaks remain undetermined even after extensive testing. Similarly, on average, approximately 40% of the cases of sporadic diarrhea are unexplained. It is therefore evident that additional infectious agents associated with diarrhea remain undiscovered.
The present invention relates to an additional infectious agent associated with diarrhea which provides a further means to diagnose, prevent and treat this condition. This agent, designated Astrovirus VA1 (AstV-VA1), was identified and sequenced as associated with a gastroenteritis outbreak at a child care center.
Astroviruses are a family of small, single-stranded, positive-sense RNA viruses. Their genomes are organized into three open reading frames denoted ORF's 1a, 1b, and 2, which encode a serine protease, RNA-dependent RNA polymerase (RdRP), and a capsid precursor protein, respectively. At both the 5′ and 3′ ends, non-translated regions (NTR) flank the 6.1-7.3 kb sized genomes. Two characteristic features of astroviruses are the dependency on a ribosomal frameshift for the translation of ORF1b and the generation of a sub-genomic RNA from which ORF2 is translated.